The University of Pennsylvania Program on Molecular Susceptibility to Hormone-Induced Cancer will investigate etiologic factors related to major cancers through case-control and laboratory-based studies using the established Delaware Valley Case-Control Network. All potentially eligible cases will be identified through active surveillance of 70 hospitals serving the nine-county region of the Delaware Valley. Controls will be selected randomly from the same geographic region using random digit dialing. Each control will arise from the same source population that gave rise to the causes, thus minimizing selection bias, which is of great concern in any case-control study. The goal of the Hospital Network Core is to organize and implement the case accrual and hospital-based data collection activities for the Program. By centralizing the hospital-based data collection to the Hospital Network Core, we will avoid duplication of effort, achieving significant gains in efficiency and enhancing the validity of data collected. All hospital-based activities are the primary responsibility of the Hospital Network Core, including IRB approval, case ascertainment, obtaining physician approval, and medical record review. First, the Hospital Network Core will set up case ascertainment and medical record review systems in all 70 Network hospitals. Hospital Network Core Nurse Coordinators will collect standard information necessary to establish initial case eligibility from multiple hospital sources, including pathology, tumor registry, medical records, radiology, surgery, and admissions office. For Project 3, women with benign breast disease will be identified through pathology and breast surgeons' offices. Second, the Hospital Network Core will implement and monitor sampling procedures for cases, when appropriate (Project 1). Third, the Nurse Coordinators and Core Director will obtain individual physician approval to recruit potentially eligible cases before referring them to the Field Core for enrollment. In addition, Hospital Network Core Nurse Coordinators will carry out in-depth medical record abstraction to collect additional information necessary to classify stage of tumor at diagnosis. The Hospital Network Core will carry out formal quality control assessments of case ascertainment, eligibility determination, and medical record reviews. Finally, the Hospital Network Core will train and retrain ore staff throughout the data collection period. During the final year of the Program, Hospital Network Core staff will participate in data analysis and in formal evaluation of the efficiency of the Program design and the methodological issues that arise.